3D numerical modelling of concrete structural element reinforced with ribbed flat steel rebars

Self Cite

This paper introduces a new approach to model cracking processes in large reinforced concrete structures, like dams or nuclear power plants. For these types of structures it is unreasonable, due to calculation time, to explicitly model rebars and steel-concrete bonds. To solve this problem, we developed, in the framework of the finite element method, a probabilistic macroscopic cracking model based on a multiscale simulation strategy: the probabilistic model for (finite) elements of reinforced concrete (PMERC). The PMERC's identification strategy is case-specific because it holds information about the local behavior, obtained in advance via numerical experimentations. This information is then projected to the macroscopic finite element scale via inverse analysis. The numerical experimentations are performed using a validated cracking model allowing a fine description of the cracking processes. The method used in the inverse analysis is inspired from regression (supervised learning) algorithms: data on the local scale-the training data coupled with working knowledge of the mechanical problem-would shape the macroscopic model. Although the identification phase can be relatively time-consuming, the structural simulation is as a result, very fast, leading to a sensitive reduction of the overall computational time. It is proposed a first validation of this multiscale modeling strategy on a reinforced concrete slab-beam subjected to three-point bending. We achieved promising results in terms of global behavior and macrocracking (mainly crack openings), and an important reduction in calculation time-up to 99% reduction! So we believe this is a promising approach to solve bigger and more complex structures in shorter time.

“…A simple and robust model has been developed and validated at IFSTTAR . It takes into account the nonlinear behavior of the concrete–rebar bond in the frame of damage mechanics.…”

Section: The Probabilistic Explicit Cracking Model and The Steel–concmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Numerical strategy for developing a probabilistic model for elements of reinforced concrete

Nader¹,

Rossi²,

Tailhan³

2017

Self Cite

“…Although simplifying assumptions can be made, it is very difficult to estimate the true stiffness of a partially fractured member for any given design load, in particular, because the concrete between cracks still plays a significant role in transferring tensile stresses—which is usually known as the “tension stiffening effect.” Design codes require serviceability checks to be performed for crack openings and the overall deflection of a member, in which case reliable predictions can be rather difficult and include important deviations. For this reason, models have to be validated for their ability to predict crack patterns and openings for a wide range of situations and loads …”

Section: Introductionmentioning

confidence: 99%

“…For this reason, models have to be validated for their ability to predict crack patterns and openings for a wide range of situations and loads. 1,2 In recent decades, the research community has witnessed the introduction of many computational approaches for predicting the fracture behavior of different materials with the discrete representation of cracks. Theoretically, there are now several numerical techniques that can be used within the scope of the finite element method.…”

Section: Introductionmentioning

confidence: 99%

Numerical modeling of concrete beams under serviceability conditions with a discrete crack approach and noniterative solution‐finding algorithms

Dias-da-Costa

Carmo

Graça-e-Costa

2017

This paper describes the development and validation of a comprehensive numerical model enabling the simulation of reinforced concrete beams under serviceability conditions using a discrete crack approach. The highly nonlinear behavior introduced by the different material models and the many localized cracks propagating within the member pose a challenge to classic iterative solvers, which often fail to converge. This limitation is solved using a noniterative solution‐finding algorithm to overcome critical bifurcation points. The finite element model was validated using experimental data on lightweight aggregate concrete beams under flexural loading. It was shown that the model properly simulates both the overall and localized features of the structural response, including curvature, crack openings, and crack patterns. The model was used to carry out a numerical study of the role of longitudinal reinforcement ratios and crack widths in reinforced concrete beams. It was observed that the total crack openings along a member seem to remain nearly independent of the tensile reinforcement for ratios >2.5% and the same level of strength.

“…15 Recent advancements in computer technology and the advent of several computer programs for modeling of structural systems have provided engineers and researchers with the possibility of getting deeper into numerical analyses. 16,17 A very interesting and powerful feature in ANSYS is its contact technology which is capable of simulating the interactive behavior between two different material surfaces in an integrated mode. 18 Bond behavior depends on a variety factors and parameters, such as concrete cover, 19 casting direction, 20 bar size, 21 concrete quality, 3 lateral confinement, 22 etc.…”

mentioning

confidence: 99%

Basic parameters test and 3D modeling of bond between high‐strength concrete and ribbed steel bar after elevated temperatures

Zhao

Zhu²

2017

This paper presents basic parameters test and an efficient numerical model for the bond between reinforcing bars and concrete after elevated temperatures. The chemical adhesive and friction coefficient are measured by self‐designed setups, and the variation law of the parameters is summarized. In the 3D modeling, bar‐to‐concrete interface has been modeled by means of an explicit discretization of the bar ribs. Surface‐to‐surface contact pair elements are employed for the interface, and the tangential contact behavior is elastic‐plastic with a Coulomb‐type friction model. Comparison between experimental and numerical results shows that the proposed model describes the behavior of steel bar relatively well in the pull‐out process after elevated temperatures. The 3D modeling makes up some deficiencies of macro pull‐out test, such as the detailed stress distributions and crack patterns.